Compositions of pigment concentrates in phase change inks

ABSTRACT

Compositions of pigment concentrate suitable for phase change ink comprising a an ink base and an amine based dispersant. Particularly, the ink base includes a diester crystalline compound having a structure of Formula I: 
     
       
         
         
             
             
         
       
         
         wherein each R 1 , R 2 , R 3 , and R 4  is independently H or alkyl; p is from about 1 to about 40, and q is from about 1 to about 40.

CROSS-REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly owned U.S. patent application Ser. No.13/680,716 now U.S. Pat. No. 8,758,494 issued on June 24, 2014 entitled“Pigmented Magenta and Yellow Phase Change Inks” to Daryl W. Vanbesienet al., electronically filed on the same day herewith.

BACKGROUND

The present embodiments relate to solid ink compositions characterizedby being solid at room temperature and molten at an elevated temperatureat which the molten ink is applied to a substrate. These solid inkcompositions can be used for ink jet printing. The present embodimentsare directed to solid ink compositions comprising an amorphous compound,a crystalline compound, and a pigment concentrate, and methods of makingthe same.

Ink jet printing processes may employ inks that are solid at roomtemperature and liquid at elevated temperatures. Such inks may bereferred to as solid inks, hot melt inks, phase change inks and thelike. For example, U.S. Pat. No. 4,490,731, the disclosure of which istotally incorporated herein by reference, discloses an apparatus fordispensing solid ink for printing on a recording medium such as paper.In piezo ink jet printing processes employing hot melt inks, the solidink is melted by the heater in the printing apparatus and utilized(jetted) as a liquid in a manner similar to that of conventional piezoink jet printing. Upon contact with the printing recording medium, themolten ink solidifies rapidly, enabling the colorant to substantiallyremain on the surface of the recording medium instead of being carriedinto the recording medium (for example, paper) by capillary action,thereby enabling higher print density than is generally obtained withliquid inks. Advantages of a phase change ink in ink jet printing arethus elimination of potential spillage of the ink during handling, awide range of print density and quality, minimal paper cockle ordistortion, and enablement of indefinite periods of nonprinting withoutthe danger of nozzle clogging, even without capping the nozzles.

In general, phase change inks (sometimes referred to as “hot melt inks”or “solid inks”) are in the solid phase at ambient temperature, butexist in the liquid phase at the elevated operating temperature of anink jet printing device. At the jetting temperature, droplets of liquidink are ejected from the printing device and, when the ink dropletscontact the surface of the recording medium, either directly or via anintermediate heated transfer belt or drum, they quickly solidify to forma predetermined pattern of solidified ink drops.

Phase change inks for color printing typically comprise a phase changeink carrier composition which is combined with a phase change inkcompatible colorant. In a specific embodiment, a series of colored phasechange inks can be formed by combining ink carrier compositions withcompatible subtractive primary colorants. The subtractive primarycolored phase change inks can comprise four component dyes or pigments,namely, cyan, magenta, yellow and black, although the inks are notlimited to these four colors. These subtractive primary colored inks canbe formed by using a single dye or pigment or a mixture of dyes orpigments.

Phase change inks are desirable for ink jet printers because they remainin a solid phase at room temperature during shipping, long term storage,and the like. In addition, the problems associated with nozzle cloggingas a result of ink evaporation with liquid ink jet inks are largelyeliminated, thereby improving the reliability of the ink jet printing.Further, in phase change ink jet printers wherein the ink droplets areapplied directly onto the final recording medium (for example, paper,transparency material, and the like), the droplets solidify immediatelyupon contact with the recording medium, so that migration of ink alongthe printing medium is prevented and dot quality is improved.

Crystalline-amorphous phase change inks disclosed in U.S. patentapplication Ser. No. 13/095,636 filed on Apr. 27, 2011 display improvedrobustness on coated substrates with respect to scratch, fold and foldoffset. While the above conventional solid ink technology is generallysuccessful in producing vivid images and providing economy of jet useand substrate latitude on porous papers, such technology has not beensatisfactory for certain pigmented inks. For example, yellow and magentapigments are particularly difficult to be dispersed as they sharesimilar hydrogen bonding structures with certain crystalline diurethanecomponents in the inks (e.g., dibenzyl hexane-1,6-diyldicarbamate hereincalled DHDC). Thus, there exists a need to develop a crystallinematerial that is more compatible with yellow and magenta pigments; assuch the yellow and magenta pigments can be dispersed satisfactorily toform phase change inks. In the present disclosure, compositions ofpigment concentrate containing an improved crystalline material that ismore compatible particularly with yellow and magenta pigments will bediscussed.

Each of the foregoing U.S. patents and patent publications areincorporated by reference herein. Further, the appropriate componentsand process aspects of the each of the foregoing U.S. patents and patentpublications may be selected for the present disclosure in embodimentsthereof.

SUMMARY

According to embodiments illustrated herein, there is provided pigmentconcentrate comprising an ink base and an amine based dispersant,wherein the ink base comprises a crystalline compound having a structureof Formula I:

-   wherein each R₁, R₂, R₃, R₄ is independently H or alkyl; p is from    about 1 to about 40, and q is from about 1 to about 40.

In particular, the present embodiments provide pigment concentratecomprising a crystalline compound having a structure of Formula I asdescribed above; an amine based dispersant having a structure of FormulaII:

-   wherein x is from about 1 to about 10, and y is from about 10 to    about 10,000; and a pigment.

In further embodiments, there is provided pigment concentrate comprisinga crystalline compound having a structure of Formula I as describedabove; an amine based dispersant having a structure of Formula II asdescribed above; and a pigment selected from the group consisting ofcyan, magenta, yellow, black, and mixtures thereof; and a pigmentsynergist.

DETAILED DESCRIPTION

In the following description, it is understood that other embodimentsmay be utilized and structural and operational changes may be madewithout departure from the scope of the present embodiments disclosedherein.

The present embodiments provide a composition of pigment concentrate fora phase change ink. The pigment concentrate includes an ink base, and anamide based dispersant, where the ink base may include a crystallinecompound. The ink base may further include an amorphous compound.

The Pigment Concentrate

In certain embodiments, the pigment concentrate includes a diestercrystalline compound having a structure of Formula I:

-   wherein each R₁, R₂, R₃, and R₄ can be independently H or alkyl, p    is from about 1 to about 40, and q is from about 1 to about 40. In    certain of such embodiments, p is from about 10 to about 30, from    about 14 to about 20, or from about 16 to about 18. In certain of    such embodiments, q is from about 10 to about 30, from about 14 to    about 20, or from about 16 to about 18. In certain embodiments, p    and q may or may not be the same. In certain embodiments, each R₁,    R₂, R₃, and R₄ can be independently H or lower alkyl such as methyl,    ethyl, propyl, isopropyl, butyl, isobutyl or t-butyl. In one    embodiment, each R₁, R₂, R₃, and R₄ is H. In a specific embodiment,    the diester compound includes distearylterephthalate (DST) having    the following structure:

The crystalline compound in the pigment concentrate may be present in anamount of from about 25 percent weight to about 90 percent weight, fromabout 40 percent weight to about 80 percent weight, or from about 50percent weight to about 70 percent weight, based on the total weight ofthe pigment concentrate.

The pigment concentrate further includes an amine based dispersant. Incertain embodiments, the amine based dispersant has a structure ofFormula II:

-   wherein x is from about 1 to about 10, and y is from about 10 to    about 10,000. In certain of such embodiments, x is from about 2 to    about 8 or from about 3 to about 5. In certain of such embodiments,    y is from about 5 to about 20 or from about 9 to about 14. In a    specific embodiment, the amine based dispersant has the following    structure:

-   wherein y is from about 9 to about 14 (Compound A).

The dispersant in the pigment concentrate may be present in an amount offrom about 2 percent weight to about 40 percent weight, from about 5percent weight to about 35 percent weight, or from about 10 percentweight to about 30 percent weight based on the total weight of thepigment concentrate.

The pigment concentrate may further include a colorant such as dyes orpigments. The colorants can be either from the cyan, magenta, yellow,black (CMYK) set or from spot colors obtained from custom color dyes orpigments or mixtures of pigments. Dye-based colorants are miscible withthe ink base composition, which comprises the crystalline and amorphouscomponents and any other additives.

Any desired or effective colorant can be employed in the phase changeink compositions, including dyes, pigments, mixtures thereof, and thelike, provided that the colorant can be dissolved or dispersed in theink carrier. Any dye or pigment may be chosen, provided that it iscapable of being dispersed or dissolved in the ink carrier and iscompatible with the other ink components. The phase change carriercompositions can be used in combination with conventional phase changeink colorant materials, such as Color Index (C.I.) Solvent Dyes,Disperse Dyes, modified Acid and Direct Dyes, Basic Dyes, Sulphur Dyes,Vat Dyes, and the like. Examples of suitable dyes include Neozapon Red492 (BASF); Orasol Red G (Pylam Products); Direct Brilliant Pink B(Oriental Giant Dyes); Direct Red 3BL (Classic Dyestuffs); SupranolBrilliant Red 3BW (Bayer AG); Lemon Yellow 6G (United Chemie); LightFast Yellow 3G (Shaanxi); Aizen Spilon Yellow C-GNH (Hodogaya Chemical);Bemachrome Yellow GD Sub (Classic Dyestuffs); Cartasol Brilliant Yellow4GF (Clariant); Cibanone Yellow 2G (Classic Dyestuffs); Orasol Black RLI(BASF); Orasol Black CN (Pylam Products); Savinyl Black RLSN (Clariant);Pyrazol Black BG (Clariant); Morfast Black 101 (Rohm & Haas); DiaazolBlack RN (ICI); Thermoplast Blue 670 (BASF); Orasol Blue GN (PylamProducts); Savinyl Blue GLS (Clariant); Luxol Fast Blue MBSN (PylamProducts); Sevron Blue 5GMF (Classic Dyestuffs); Basacid Blue 750(BASF); Keyplast Blue (Keystone Aniline Corporation); Neozapon Black X51(BASF); Classic Solvent Black 7 (Classic Dyestuffs); Sudan Blue 670(C.I. 61554) (BASF); Sudan Yellow 146 (C.I. 12700) (BASF); Sudan Red 462(C.I. 26050) (BASF); C.I. Disperse Yellow 238; Neptune Red Base NB543(BASF, C.I. Solvent Red 49); Neopen Blue FF-4012 (BASF); Fatsol Black BR(C.I. Solvent Black 35) (Chemische Fabriek Triade BV); Morton MorplasMagenta 36 (C.I. Solvent Red 172); metal phthalocyanine colorants suchas those disclosed in U.S. Pat. No. 6,221,137, the disclosure of whichis totally incorporated herein by reference, and the like. Polymericdyes can also be used, such as those disclosed in, for example, U.S.Pat. Nos. 5,621,022 and 5,231,135, the disclosures of each of which areherein entirely incorporated herein by reference, and commerciallyavailable from, for example, Milliken & Company as Milliken Ink Yellow869, Milliken Ink Blue 92, Milliken Ink Red 357, Milliken Ink Yellow1800, Milliken Ink Black 8915-67, uncut Reactint Orange X-38, uncutReactint Blue X-17, Solvent Yellow 162, Acid Red 52, Solvent Blue 44,and uncut Reactint Violet X-80.

Pigments are also suitable colorants for the phase change inks. Examplesof suitable pigments include PALIOGEN Violet 5100 (BASF); PALIOGENViolet 5890 (BASF); HELIOGEN Green L8730 (BASF); LITHOL Scarlet D3700(BASE); SUNFAST Blue 15:4 (Sun Chemical); Hostaperm Blue B2G-D(Clariant); Hostaperm Blue B4G (Clariant); Permanent Red P-F7RK;Hostaperm Violet BL (Clariant); LITHOL Scarlet 4440 (BASF); Bon Red C(Dominion Color Company); ORACET Pink RF (BASF); PALIOGEN Red 3871 K(BASF); SUNFAST Blue 15:3 (Sun Chemical); PALIOGEN Red 3340 (BASF);SUNFAST Carbazole Violet 23 (Sun Chemical); LITHOL Fast Scarlet L4300(BASF); SUNBRITE Yellow 17 (Sun Chemical); HELIOGEN Blue L6900, L7020(BASF); SUNBRITE Yellow 74 (Sun Chemical); SPECTRA PAC C Orange 16 (SunChemical); HELIOGEN Blue K6902, K6910 (BASF); SUNFAST Magenta 122 (SunChemical); HELIOGEN Blue D6840, D7080 (BASF); Sudan Blue OS (BASF);NEOPEN Blue FF4012 (BASF); PV Fast Blue B2GO1 (Clariant); IRGALITE BlueGLO (BASF); PALIOGEN Blue 6470 (BASF); Sudan Orange G (Aldrich); SudanOrange 220 (BASF); PALIOGEN Orange 3040 (BASF); PALIOGEN Yellow 152,1560 (BASF); LITHOL Fast Yellow 0991 K (BASF); PALIOTOL Yellow 1840(BASF); NOVOPERM Yellow FGL (Clariant); Ink Jet Yellow 4G VP2532(Clariant); Toner Yellow HG (Clariant); Lumogen Yellow D0790 (BASF);Suco-Yellow L1250 (BASF); Suco-Yellow D1355 (BASF); Suco Fast YellowD1355, D1351 (BASF); HOSTAPERM Pink E 02 (Clariant); Hansa BrilliantYellow 5GX03 (Clariant); Permanent Yellow GRL 02 (Clariant); PermanentRubine L6B 05 (Clariant); FANAL Pink D4830 (BASF); CINQUASIA Magenta (DUPONT); PALIOGEN Black L0084 (BASF); Pigment Black K801 (BASF); andcarbon blacks such as REGAL 330™ (Cabot), Nipex 150 (Evonik) CarbonBlack 5250 and Carbon Black 5750 (Columbia Chemical), and the like, aswell as mixtures thereof.

In certain embodiments, the pigment concentrate contains yellow pigmentssuch as PY155 and PY180 which are shown below:

and mixtures thereof.

In certain embodiments, the pigment concentrate contains magenta/redpigments such as PR57:1 (the counter ion can be various including Ca,Sr, etc.) which are shown below:

and mixtures thereof.

Pigment concentrates in the ink base may be stabilized by synergists anddispersants. A pigment synergist is a substance that aims in improvingpigment dispersion and stability. Typically, a pigment synergiststrengthens the attachment of dispersants to the pigment surface andhelps to stabilize the pigment particles within the ink base.

Solsperse 22000, available from Lubrizol, is an example of pigmentsynergist, which is a polymeric material.

Also suitable are the colorants disclosed in U.S. Pat. Nos. 6,472,523,6,726,755, 6,476,219, 6,576,747, 6,713,614, 6,663,703, 6,755,902,6,590,082, 6,696,552, 6,576,748, 6,646,111, 6,673,139, 6,958,406,6,821,327, 7,053,227, 7,381,831 and 7,427,323, the disclosures of eachof which are incorporated herein by reference in their entirety.

In embodiments, solvent dyes are employed. An example of a solvent dyesuitable for use herein may include spirit soluble dyes because of theircompatibility with the ink carriers disclosed herein. Examples ofsuitable spirit solvent dyes include Neozapon Red 492 (BASF); Orasol RedG (Pylam Products); Direct Brilliant Pink B (Global Colors); AizenSpilon Red C-BH (Hodogaya Chemical); Kayanol Red 3BL (Nippon Kayaku);Spirit Fast Yellow 3G; Aizen Spilon Yellow C-GNH (Hodogaya Chemical);Cartasol Brilliant Yellow 4GF (Clariant); Pergasol Yellow 5RA EX(Classic Dyestuffs); Orasol Black RLI (BASF); Orasol Blue GN (PylamProducts); Savinyl Black RLS (Clariant); Morfast Black 101 (Rohm andHaas); Thermoplast Blue 670 (BASF); Savinyl Blue GLS (Sandoz); LuxolFast Blue MBSN (Pylam); Sevron Blue 5GMF (Classic Dyestuffs); BasacidBlue 750 (BASF); Keyplast Blue (Keystone Aniline Corporation); NeozaponBlack X₅₁ (C.I. Solvent Black, C.I. 12195) (BASF); Sudan Blue 670 (C.I.61554) (BASF); Sudan Yellow 146 (C.I. 12700) (BASF); Sudan Red 462 (C.I.260501) (BASF), mixtures thereof and the like.

The pigment concentrate has a particle size of an average diameter offrom about 50 nm to about 400 nm, from about 90 nm to about 300 nm, orfrom 100 nm to about 280 nm. The pigment concentrate has a viscosity at140° C. of from about 10 centipoise to about 100 centipoise.

A phase change ink can be prepared by including the pigment concentrateof the present embodiments, an amorphous component and a crystallinecomponent. Thus, in embodiments, the amorphous compounds are formulatedwith a crystalline compound to form a phase change ink composition. Theamorphous component may or may not be the same as the amorphous materialpresent in the pigment concentrate (if any). The crystalline componentmay or may not be the same as the crystalline material present in thepigment concentrate.

In embodiments, the crystalline component is a di-ester compounds madefrom Scheme 1 below.

wherein R is a saturated or ethylenically unsaturated aliphatic group inone embodiment with at least about 6 carbon atoms, and in anotherembodiment with at least about 8 carbon atoms, and in one embodimentwith no more than about 100 carbon atoms, in another embodiment with nomore than about 80 carbon atoms, and in yet another embodiment with nomore than about 60 carbon atoms, although the number of carbon atoms canbe outside of these ranges, In a specific embodiment, the crystallinecompound is derived from natural fatty alcohols such as octanol, stearylalcohol, lauryl alcohol, behenyl alcohol, myristyl alcohol, capricalcohol, linoleyl alcohol, and the like. The above reaction may beconducted by combining dimethyl terepthalate and alcohol in the melt inthe presence of a tin catalyst, such as, dibutyl tin dilaurate (Fascat4202), dibutyl tin oxide (Fascat 4100); a zinc catalyst, such as Bi catZ; or a bismuth catalyst, such as Bi cat 8124; Bi cat 8108, a titaniumcatalyst such as titanium dioxide Only trace quantities of catalyst arerequired for the process.

In embodiments, the catalyst is present in an amount of about 0.01weight percent to 2 weight percent or of about 0.05 weight percent toabout 1 weight percent of the total product.

The reaction is carried out at an elevated temperature of about 150° C.to about 250° C. or from about 160° C. to about 210° C. The solvent-freeprocess is environmentally sustainable and eliminates problems withbyproducts and also means higher reactor throughput.

In embodiments, the amorphous component is an ester of tartaric acidhaving a formula of Formula III

-   wherein R₁ and R₂ each, independently of the other or meaning that    they can be the same or different, is selected from the group    consisting of alkyl group, wherein the alkyl portion can be    straight, branched or cyclic, saturated or unsaturated, substituted    or unsubstituted, having from about 1 to about 40 carbon atoms or a    substituted or unsubstituted aromatic or heteroaromatic group, and    mixtures thereof. In certain embodiments, each R₁ and R₂ is    independently a cyclohexyl group optionally substituted with one or    more alkyl group(s) selected from methyl, ethyl, n-propyl,    isopropyl, n-butyl and t-butyl.

The tartaric acid backbone is selected from L-(+)-tartaric acid,D-(−)-tartaric acid, DL-tartaric acid, or mesotartaric acid, andmixtures thereof. Depending on the R groups and the stereochemistries oftartaric acid, the esters could form crystals or stable amorphouscompounds. In specific embodiments, the amorphous compound is selectedfrom the group consisting of di-L-menthyl L-tartrate, di-DL-menthylL-tartrate (DMT), di-L-menthyl DL-tartrate, di-DL-menthyl DL-tartrate,and any stereoisomers and mixtures thereof.

These materials show, relatively low viscosity (<10² centipoise (cps),or from about 1 to about 100 cps, or from about 5 to about 95 cps) nearthe jetting temperature (≦140° C., or from about 100 to about 140° C.,or from about 105 to about 140° C.) but very high viscosity (>10⁵ cps)at room temperature.

To synthesize the amorphous component, tartaric acid was reacted with avariety of alcohols to make di-esters as shown in the synthesis schemeshown in U.S. patent application Ser. No. 13/095,784. Suitable alcoholsto be used with the present embodiments may be selected from the groupconsisting of alkyl alcohol, wherein the alkyl portion of the alcoholcan be straight, branched or cyclic, saturated or unsaturated,substituted or unsubstituted, having from about 1 to about 40 carbonatoms, or a substituted or unsubstituted aromatic or heteroaromaticgroup, and mixtures thereof. A variety of alcohols may be used in theesterification such as, for example, menthol, isomenthol, neomenthol,isoneomentholand any stereoisomers and mixtures thereof. Mixtures ofaliphatic alcohols may be used in the esterification. For example, amixture of two aliphatic alcohols may be used in the esterification.Suitable examples of aliphatic alcohols that can be used in these mixedreactions are cyclohexanol and substituted cyclohexanols (e.g., 2-, 3-or 4-t-butyl cyclohexanol). The molar ratios of the aliphatic alcoholsmay be from 25:75 to 75:25, from 40:60 to 60:40, or about 50:50.

Some more suitable amorphous materials are disclosed in U.S. patentapplication Ser. No. 13/680,200 to Goredema et al., which is herebyincorporated by reference in its entirety.

The amorphous components provide tackiness and impart robustness to theprinted ink. In the present embodiments, desirable amorphous materialshave relatively low viscosity (<102 cps, or from about 1 to about 100cps, or from about 5 to about 95 cps) at about 140° C., but very highviscosity (>106 cps) at room temperature. The low viscosity at 140° C.provides wide formulation latitude while the high viscosity at roomtemperature imparts robustness. The amorphous components have Tgs (glasstransition temperatures) but do not exhibit crystallization and meltingpeaks by DSC (10° C./min from −50 to 200 to −50° C.). The Tg values aretypically from about 10 to about 50° C., or from about 10 to about 40°C., or from about 10 to about 35° C., to impart the desired toughnessand flexibility to the inks. The selected amorphous materials have lowmolecular weights, such as less than 1000 g/mol, or from about 100 toabout 1000 g/mol, or from about 200 to about 1000 g/mol, or from about300 to about 1000 g/mol. Higher molecular weight amorphous materialssuch as polymers become viscous and sticky liquids at high temperatures,but have viscosities that are too high to be jettable with piezoelectricprintheads at desirable temperatures.

In specific embodiments, the amorphous binder is a di-ester of mentholand tartaric acid (DMT). In other embodiments, the amorphous binder isan ester of a mixture of cyclohexanol and t-butylcyclohexanol (50:50ratio) and tartaric acid, t-butylcylohexyl-cyclohexyl tartrate (TBCT).DMT and TBCT are disclosed in U.S. patent application Ser. No.13/095,784 to Morimitsu et al., which is hereby incorporated byreference in its entirety.

DMT (dimenthyl tartrate) has a general structure as follows.

Specific stereoiosmers of DMT include compounds illustrated in Table 1.

TABLE 1 Tg η @ 140° C. MW Compound Structure (° C.)* (cps)** (g/mol) 5

19 10 426.59 6

18 10 426.59 7

13 10 426.59 Target 10-50° C. <100 cps <1000 g/mol *The samples weremeasured on a Q1000 Differential Scanning Calorimeter (TA Instruments)at a rate of 10° C./min from −50° C. to 200° C. to −50° C.; midpointvalues are quoted. **The samples were measured on a RFS3 controlledstrain Rheometer (TA instruments) equipped with a Peltier heating plateand using a 25 mm parallel plate. The method used was a temperaturesweep from high to low temperatures, in temperature decrements of 5° C.,a soak (equilibration) time of 120 seconds between each temperature andat a constant frequency of 1 Hz.

TBCT (t-butylcylohexyl-cyclohexyl tartrate) has a general structure asfollows.

Specific stereoisomers of TBCT include:

The amorphous compounds show relatively low viscosity (<10² centipoise(cps), or from about 1 to about 100 cps, or from about 5 to about 95cps) near the jetting temperature (≦140° C.) but very high viscosity(>10⁵ cps) at room temperature.

In embodiments, the amorphous component is present an amount of fromabout 2 percent to about 50 percent by weight, or from about 5 percentto about 40 percent by weight, or from about 10 percent to about 30percent by weight of the total weight of the ink composition.

In embodiments, the crystalline component is present in an amount offrom about 60 percent to about 95 percent by weight, or from about 65percent to about 95 percent by weight, or from about 70 percent to about90 percent by weight of the total weight of the ink composition.

Typically, the weight ratio of the crystalline component to theamorphous component is from about 65:40 to about 95:5, from about 70:30to about 90:10, or from about 75:25 to about 85:15.

All of the crystalline component and binders are esters. This class ofmaterials is well known to be readily biodegradable. The inkcompositions show good rheological profiles. Print samples created bythe solid ink composition on coated paper by K-proof exhibit excellentrobustness.

In embodiments, the solid inks meet certain specific physicalproperties. For example, the solid inks of the present embodiments havea melting point (T_(melt))<150° C. or from about 60° C. to about 140°C., or from about 70° C. to about 130° C. In other embodiments, the inkhas a T_(crys)>60° C. or from about 65° C. to about 110° C., or fromabout 70° C. to about 100° C. In other embodiments, the ink of thepresent embodiments has a viscosity of from about 1 to about 22 cps in ajetting range of from about 100 to about 140° C. In particular, the inkof the present embodiments has a viscosity at 140° C. of <12 cps or fromabout 12 cps to about 3 cps, or from about 10 cps to about 5 cps. Theink may have a viscosity of greater than about 10⁶ cps at roomtemperature.

The ink of embodiments may further include conventional additives totake advantage of the known functionality associated with suchconventional additives. Such additives may include, for example, atleast one antioxidant, defoamer, slip and leveling agents, clarifier,viscosity modifier, adhesive, plasticizer and the like.

The ink may optionally contain antioxidants to protect the images fromoxidation and also may protect the ink components from oxidation whileexisting as a heated melt in the ink reservoir. Examples of suitableantioxidants include N,N′-hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide) (IRGANOX 1098, available from BASF);2,2-bis(4-(2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy))ethoxyphenyl)propane (TOPANOL-205, available from Vertellus);tris(4-tert-butyl-3-hydroxy-2,6-dimethyl benzyl)isocyanurate (Aldrich);2,2′-ethylidene bis(4,6-di-tert-butylphenyl)fluoro phosphonite(ETHANOX-398, available from Albermarle Corporation);tetrakis(2,4-di-tert-butylphenyl)-4,4′-biphenyl diphosphonite (Aldrich);pentaerythritol tetrastearate (TCI America); tributylammoniumhypophosphite (Aldrich); 2,6-di-tert-butyl-4-methoxyphenol (Aldrich);2,4-di-tert-butyl-6-(4-methoxybenzyl)phenol (Aldrich);4-bromo-2,6-dimethylphenol (Aldrich); 4-bromo-3,5-didimethylphenol(Aldrich); 4-bromo-2-nitrophenol (Aldrich); 4-(diethylaminomethyl)-2,5-dimethylphenol (Aldrich); 3-dimethylaminophenol(Aldrich); 2-amino-4-tert-amylphenol (Aldrich);2,6-bis(hydroxymethyl)-p-cresol (Aldrich); 2,2′-methylenediphenol(Aldrich); 5-(diethylamino)-2-nitrosophenol (Aldrich);2,6-dichloro-4-fluorophenol (Aldrich); 2,6-dibromo fluoro phenol(Aldrich); α-trifluoro-o-cresol (Aldrich); 2-bromo-4-fluorophenol(Aldrich); 4-fluorophenol (Aldrich);4-chlorophenyl-2-chloro-1,1,2-tri-fluoroethyl sulfone (Aldrich);3,4-difluoro phenylacetic acid (Adrich); 3-fluorophenylacetic acid(Aldrich); 3,5-difluoro phenylacetic acid (Aldrich);2-fluorophenylacetic acid (Aldrich); 2,5-bis(trifluoromethyl)benzoicacid (Aldrich);ethyl-2-(4-(4-(trifluoromethyl)phenoxy)phenoxy)propionate (Aldrich);tetrakis (2,4-di-tert-butyl phenyl)-4,4′-biphenyl diphosphonite(Aldrich); 4-tert-amyl phenol (Aldrich);3-(2H-benzotriazol-2-yl)-4-hydroxy phenethylalcohol (Aldrich); NAUGARD76, NAUGARD 445, NAUGARD 512, and NAUGARD 524 (manufactured by ChemturaCorporation); and the like, as well as mixtures thereof. Theantioxidant, when present, may be present in the ink in any desired oreffective amount, such as from about 0.25 percent to about 10 percent byweight of the ink or from about 1 percent to about 5 percent by weightof the ink.

The colorant may be present in the phase change ink in any desired oreffective amount to obtain the desired color or hue such as, forexample, at least from about 0.1 percent by weight of the ink to about50 percent by weight of the ink, at least from about 0.2 percent byweight of the ink to about 20 percent by weight of the ink, and at leastfrom about 0.5 percent by weight of the ink to about 10 percent byweight of the ink.

The ink compositions can be prepared by any desired or suitable method.For example, each of the components of the ink carrier can be mixedtogether, followed by heating, the mixture to at least its meltingpoint, for example from about 60° C. to about 150° C., 80° C. to about145° C. and 85° C. to about 140° C. The colorant may be added before theink ingredients have been heated or after the ink ingredients have beenheated. When pigments are the selected colorants, the molten mixture maybe subjected to grinding in an attritor or media mill apparatus toeffect dispersion of the pigment in the ink carrier. The heated mixtureis then stirred for about 5 seconds to about 30 minutes or more, toobtain a substantially homogeneous, uniform melt, followed by coolingthe ink to ambient temperature (typically from about 20° C. to about 25°C.). The inks are solid at ambient temperature. The inks can be employedin apparatus for direct printing ink jet processes and in indirect(offset) printing ink jet applications. Another embodiment disclosedherein is directed to a process which comprises incorporating an ink asdisclosed herein into an ink jet printing apparatus, melting the ink,and causing droplets of the melted ink to be ejected in an imagewisepattern onto a recording substrate. A direct printing process is alsodisclosed in, for example, U.S. Pat. No. 5,195,430, the disclosure ofwhich is totally incorporated herein by reference. Yet anotherembodiment disclosed herein is directed to a process which comprisesincorporating an ink as disclosed herein into an ink jet printingapparatus, melting the ink, causing droplets of the melted ink to beejected in an imagewise pattern onto an intermediate transfer member,and transferring the ink in the imagewise pattern from the intermediatetransfer member to a final recording substrate. In a specificembodiment, the intermediate transfer member is heated to a temperatureabove that of the final recording sheet and below that of the melted inkin the printing apparatus. In another specific embodiment, both theintermediate transfer member and the final recording sheet are heated;in this embodiment, both the intermediate transfer member and the finalrecording sheet are heated to a temperature below that of the melted inkin the printing apparatus; in this embodiment, the relative temperaturesof the intermediate transfer member and the final recording sheet can be(1) the intermediate transfer member is heated to a temperature abovethat of the final recording substrate and below that of the melted inkin the printing apparatus; (2) the final recording substrate is heatedto a temperature above that of the intermediate transfer member andbelow that of the melted ink in the printing apparatus; or (3) theintermediate transfer member and the final recording sheet are heated toapproximately the same temperature. An offset or indirect printingprocess is also disclosed in, for example, U.S. Pat. No. 5,389,958, thedisclosure of which is totally incorporated herein by reference. In onespecific embodiment, the printing apparatus employs a piezoelectricprinting process wherein droplets of the ink are caused to be ejected inimagewise pattern by oscillations of piezoelectric vibrating elements.Inks as disclosed herein can also be employed in other hot melt printingprocesses, such as hot melt acoustic ink jet printing, hot melt thermalink jet printing, hot melt continuous stream or deflection ink jetprinting, and the like. Phase change inks as disclosed herein can alsobe used in printing processes other than hot melt ink jet printingprocesses.

Any suitable substrate or recording sheet can be employed, includingplain papers such as XEROX 4200 papers, XEROX Image Series papers,Courtland 4024 DP paper, ruled notebook paper, bond paper, silica coatedpapers such as Sharp Company silica coated paper, JuJo paper, HAMMERMILLLASERPRINT paper, and the like, glossy coated papers such as XEROXDigital Color Elite Gloss, Sappi Warren Papers LUSTROGLOSS, specialtypapers such as Xerox DURAPAPER, and the like, transparency materials,fabrics, textile products, plastics, polymeric films, inorganicrecording mediums such as metals and wood, and the like, transparencymaterials, fabrics, textile products, plastics, polymeric films,inorganic substrates such as metals and wood, and the like.

The inks described herein are further illustrated in the followingexamples. All parts and percentages are by weight unless otherwiseindicated.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also,various presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art, and are also intended to beencompassed by the following claims.

While the description above refers to particular embodiments, it will beunderstood that many modifications may be made without departing fromthe spirit thereof. The accompanying claims are intended to cover suchmodifications as would fall within the true scope and spirit ofembodiments herein.

The presently disclosed embodiments are, therefore, to be considered inall respects as illustrative and not restrictive, the scope ofembodiments being indicated by the appended claims rather than theforegoing description. All changes that come within the meaning of andrange of equivalency of the claims are intended to be embraced therein.

EXAMPLES

The examples set forth herein below and are illustrative of differentcompositions and conditions that can be used in practicing the presentembodiments. All proportions are by weight unless otherwise indicated.It will be apparent, however, that the present embodiments can bepracticed with many types of compositions and can have many differentuses in accordance with the disclosure above and as pointed outhereinafter.

Example 1

Preparation of Compound A Dispersant

Into a 1 liter resin kettle fitted with heating mantle, mechanicalstirring, Dean-Stark trap, reflux condenser and temperature sensor wereintroduced 192.78 grams (g) of Unicid® 700 (a long chain, linearcarboxylic acid having an average carbon chain length of 48, availablefrom Baker Petrolite) and 60.3 g of E-100® (a mixture oftetraethylenepentamine, (TEPA), pentaethylenehexamine (PEHA),hexaethyleneheptamine (HEHA), and higher molecular weight materials witha number-average molecular weight of 250 to 300 grams per mole,available from Huntsman. Under a stream of Argon, the temperature in thekettle was raised to 100° C. and the resin was allowed to melt. When theresin was completely melted, the temperature was gradually raised to180° C. with stirring, and the reaction was allowed to proceed for 3hours. 3.6 milliliters of water was collected into the Dean-Stark trap.The reaction was stopped, cooled down to 140° C. and discharged to analuminum tray to give 249 g of the amide as a beige solid. Theproperties of the dispersant are shown in Table 1.

TABLE 1 Dispersant Characterization DSC Titration Onset of Peak of Peakof End of Acid Amine Crystallization Crystallization Melting Melting # #(° C.) (° C.) (° C.) (° C.) 0.87 >100 97.6 94.4 102.1 105.2 (92.6)

Synthesis of Distearyl Terephthalate (DST)

To a 2 L Buchi reactor equipped with a double turbine agitator anddistillation apparatus was charged Dimethyl terephthalate (315.8 grams),Stearyl Alcohol (879.7 grams) and heated to 130° C. under Nitrogen purgefor 1 hour, after which stirring was commenced followed by the additionof Tyzor catalyst (3.0 grams, available from Dupont). The reactionmixture was then heated to 145° C., followed by slowly ramping thetemperature to 190° C. over a 3-4 hour period such that the evolution ofmethanol is distilled in a controlled manner. The reaction temperaturewas maintained at 190° C. for an additional 16 hours until >96%conversion to the product was achieved as determined by ¹H NMRspectroscopy. The product was discharged as a low viscosity liquid whichsolidified on cooling to give a 1050 gram of a white solid (96.2%yield). The product was shown to be pure by ¹H NMR spectroscopy withtrace amounts of the mono-ester. Physical properties of this compoundare shown in Table 2

TABLE 2 T_(melt) (° C.) T_(cryst) (° C.) Viscosity at Compound (DSC)(DSC) 140° C. (cps) DST 88 79 4.5

Preparation of Pigment Concentrates

In a beaker was added an ink base (an amorphous or a crystallinecomponent), a dispersant, and optionally a pigment synergist. The choiceof ink bases and dispersants are shown in Table 3. The solution wasstirred for 30 minutes at 130° C. and was added a pigment as shown inTables 3 and 4 and stirred for an additional 1 hour at 130° C. This isreferred to as the pigment wetting phase. The resulting mixture wastransferred to a 100 mL attritor vessel containing 325 g of ⅛ inchstainless steel shots. The mixture was stirred at 350 rpm for 24 hoursat 130° C. The pigment concentrate was separated from the steel shot andmeasured for particle size.

Preparation of Inks

In a 50 mL beaker was added pigment dispersion, crystalline resin, andamorphous resin such that the ink contains 2% pigment and such that theremaining ink base crystalline to amorphous ratio is 80:20. The mixturewas then stirred at 130° C. for 2 hours and poured into a pan to freeze(solidify). The particle size and rheology were then measured. 5 gramsof ink were then placed in a vial and put into an oven set to 140° C.for one week for aging. The particle size and rheology were thenre-measured. All results are shown in Table 4 below. A successful inkshows no increase in particle size after aging, and also shows no changein rheology.

TABLE 3 Various combinations of ink bases and dispersants Ink Base: TBCTAmorphous DST Crystalline Pigment Pigment Dispersant: Concentrate FinalInk Concentrate Final Ink Solsperse Pigment Ink A Pigment No Ink 32000Concentrate (phase Concentrate (ink could A separated) C (gelled) not bemade) Compound Pigment No Ink Pigment Ink D - A Concentrate (ink couldConcentrate Cyan B (gelled) not be made) D - Cyan

TABLE 4 CMYK Dispersion and Ink Examples Ink Pigment Concentrate z-avgsize: z-avg as is/aged 7 Pigment size days at 140° C. 120 C. ViscosityColor Concentrate (nm) Ink (nm) (cps) Cyan (B4G) D-cyan 133 D-cyan130/139 8.5 Magenta B-magenta 150 B-magenta 128/145 6.2 (PR57:1) Yellow(PY180) D-yellow 180 196 D-yellow 180 213/205 8.4 Yellow (PY155)D-yelllow 261 D-yelllow 155 225/218 8.1 (7 day aged) 155 Black (Mogul L)D-Mogul L 149 D-Mogul L 113/118 7.7 Black (Mogul E) D-Mogul E 157D-Mogul E 136/141 7.5

Table 4 shows the various combinations of ink bases (TBCT amorphous orDST crystalline) and dispersants (Solsperse 32000 or Compound A) to formpigment concentrates and the resulting inks (A-D). Solsperse 32000dispersant is a polyethylimine polymer with polyester side chains,commercially available from Lubrizol Corporation, Ohio, U.S.A.

It was unsuccessful at producing a stable ink (Ink A-color) from thePigment Concentrate A prepared from Solsperse 32000 and TBCT, as Ink Awas phase separated on let-down due to the incompatibility betweenSolsperse 32000 dispersant and DST. Likewise, the preparation of PigmentConcentrate C-color, using Solsperse 32000 and a more polar DST wasunsuccessful; the mixture gelled up completely due to theincompatibility between Solsperse 32000 dispersant and TBCT.

When Compound A was used as the dispersant, it was found that theformation of dispersion (pigment concentrate) with TBCT amorphous wasunsuccessful. The resulting Pigment Concentrate B-color, (at 15%, 19%and 20% concentration) gelled up. The only combination of dispersant andink base (or milling base) that successfully produced a stable pigmentconcentrate (Pigment Concentrate D-cyan) and a stable ink (Ink D-cyan)is DST and Compound A. The combination of DST and Compound A has alsobeen shown to work well with all four colors including cyan, magenta,yellow and black to prepare stable dispersions, and subsequently stableinks with jettable viscosities below 10 cps at 120° C. (See Table 4).

The claims, as originally presented and as they may be amended,encompass variations, alternatives, modifications, improvements,equivalents, and substantial equivalents of the embodiments andteachings disclosed herein, including those that are presentlyunforeseen or unappreciated, and that, for example, may arise fromapplicants/patentees and others. Unless specifically recited in a claim,steps or components of claims should not be implied or imported from thespecification or any other claims as to any particular order, number,position, size, shape, angle, color, or material.

All the patents and applications referred to herein are herebyspecifically, and totally incorporated herein by reference in theirentirety in the instant specification.

What is claimed is:
 1. A pigment concentrate comprising an ink base andan amine based dispersant, wherein the ink base comprises a crystallinecompound having a structure of Formula I:

wherein each R₁, R₂, R₃, and R₄ is independently H or alkyl; p is fromabout 1 to about 40, and q is from about 1 to about 40 and the aminebased dispersant has a structure of Formula II:

wherein x is from about 1 to about 10, and y is from about 10 to about10,000.
 2. The pigment concentrate of claim 1, wherein each R₁, R₂, R₃,and R₄ is H.
 3. The pigment concentrate of claim 1, wherein p is fromabout 14 to about
 20. 4. The pigment concentrate of claim 1, wherein qis from about 14 to about
 20. 5. The pigment concentrate of claim 1,wherein the crystalline compound comprises distearylterephthalate. 6.The pigment concentrate of claim 1, wherein the crystalline compound inthe pigment concentrate is present in an amount of from about 25 percentweight to about 90 percent weight, based on the total weight of thepigment concentrate.
 7. The pigment concentrate of claim 1, wherein thedispersant in the pigment concentrate is present in an amount of fromabout 2 percent weight to about 40 percent weight based on the totalweight of the pigment concentrate.
 8. The pigment concentrate of claim 1further comprises a colorant.
 9. The pigment concentrate of claim 8 thecolorant is a pigment.
 10. The pigment concentrate of claim 9, whereinthe pigment is selected from the group consisting of cyan, magenta,yellow, black, and mixtures thereof.
 11. The pigment concentrate ofclaim 1 further comprises a pigment synergist.
 12. The phase change inkof claim 1, wherein the pigment concentrate has a particle size of anaverage diameter of from about 50 nm to about 400 nm.
 13. The phasechange ink of claim 1, wherein the pigment concentrate has a viscosityof between about 10 centipoise to about 100 centipoise at 140° C.
 14. Apigment concentrate comprising an amine based dispersant having astructure of Formula II:

wherein x is from about 1 to about 10, and y is from about 10 to about10,000, a crystalline compound having a structure of Formula I:

wherein each R₁, R₂, R₃, and R₄ is independently H or alkyl, p is fromabout 1 to about 40, and q is from about 1 to about 40, and a pigmentselected from the group consisting of yellow, magenta or mixturesthereof.
 15. The pigment concentrate of claim 14, wherein thecrystalline compound having a structure of Formula I:

wherein each R₁, R₂, R₃, and R₄ is independently H or alkyl; p is fromabout 10 to about 30, and q is from about 10 to about
 30. 16. Thepigment concentrate of claim 15, wherein p is from about 14 to about 20,and q is from about 14 to about
 20. 17. A pigment concentrate comprisinga crystalline compound having a structure of Formula I:

wherein each R₁, R₂, R₃, and R₄ is independently H or alkyl; p is fromabout 14 to about 20, and q is from about 14 to about 20; an amine baseddispersant having a structure of Formula II:

wherein x is 4, and y is from about 9 to about 14; and a pigmentselected from the group consisting of cyan, magenta, yellow, black, andmixtures thereof; and a pigment synergist.
 18. The pigment concentrateof claim 17, wherein the crystalline compound in the pigment concentrateis present in an amount of from about 25 percent weight to about 90percent weight based on the total weight of the pigment concentrate; andwherein the dispersant in the pigment concentrate is present in anamount of from about 2 percent weight to about 40 percent weight basedon the total weight of the pigment concentrate.